In your Sample Tests, I cannot see that you've instantiated the class User:
User user = new User();
See if this helps.

Solved it now!

Solved the issue. I read the test results wrong.
The description needs to say clearer what happens when rank 8 is reached. Of course you don't add it to the next rank, do you just store the value then? Don't minus 100? NO!! you set it to ZERO!! What a waste of time trying to solve this test!!

Hi Thanks for your feedback, noted. Yes I'm using C#. I'm aware there is no zero rank. I'm talking about where the activity rank is LOWER than the user. So the progress is either the same or +1, depending on the delta. To calculate the delta, is zero also ignored? So rank = -1, activity = 1 => is the delta 1 or 0? Or am I missing something else.

I can't pass the test where rank = -1 and activity rank = 1.
If progress is worth 1 point => it passes one test, and fails another.
If progress is worth 0 point => it fails one and passes the other. Please help! Thanks

In a test where there is a mixture of positive and negative numbers, the expected number is -14. I do not agree because there are two negative numbers, when multipled, is a positive number which is a lot bigger than -14.